Chapter 2: Problem 16
In Problems 13-16, make use of the known graph of \(y=\ln x\) to sketch the graphs of the equations. \(y=\ln (x-2)\)
Short Answer
Expert verified
Shift the graph of \( y = \ln x \) 2 units right; starts at (3,0); asymptote at \( x = 2 \).
Step by step solution
01
Understand the Parent Graph
The parent graph is for the function \( y = \ln x \). This graph is defined for all \( x > 0 \) and passes through the point (1, 0) while increasing slowly and never touching the y-axis (asymptote at \( x = 0 \)).
02
Identify the Transformation
The transformation applied to the parent graph \( y = \ln x \) is a horizontal shift. The function \( y = \ln (x-2) \) is obtained by shifting the graph of \( y = \ln x \) to the right by 2 units. This means the graph will now pass through the point (3, 0).
03
Determine Domain of Transformed Graph
The domain of \( y = \ln (x-2) \) is obtained by solving \( x-2 > 0 \). Thus, the domain is \( x > 2 \). This implies the vertical asymptote is now at \( x = 2 \).
04
Sketch the Transformed Graph
Start the graph at \( x = 2 \), which is the vertical asymptote. Plot the key point (3, 0) where the graph crosses the x-axis. Draw the curve such that it moves up to the right and approaches the x-axis, similar to the parent graph.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Natural Logarithm Function
The natural logarithm function, commonly denoted as \( y = \ln x \), is a fundamental concept in mathematics used to describe the logarithm base \( e \) of a number. The number \( e \) is an irrational constant approximately equal to 2.71828. Let's explore some of the key features and characteristics of this function:
- The natural logarithm function is only defined for positive values of \( x \). This is why the domain of \( y = \ln x \) is \( x > 0 \).
- As the input values \( x \) increase, the function \( y = \ln x \) also increases but at a gradually slower rate. This is because its derivative, \( \frac{1}{x} \), represents a decreasing function.
- A critical point on the graph of \( y = \ln x \) is \( (1, 0) \) because \( \ln 1 = 0 \).
- The graph approaches but never meets the y-axis, resulting in a vertical asymptote at \( x = 0 \).
Horizontal Shifting
Horizontal shifting is a type of transformation applied to the original graph of a function to move it left or right on the coordinate plane. For the function \( y = \ln(x - 2) \), the graph of the parent function \( y = \ln x \) is shifted horizontally. Here's how it works:
- The expression \( x - 2 \) within the natural logarithm function indicates that the entire graph shifts to the right by 2 units.
- This shift does not change the shape of the graph, but it alters both the domain and the position of the graph's key features, such as the intercepts and asymptotes.
- The point where the graph crosses the x-axis, initially at \( (1, 0) \) on the parent graph, now moves to \( (3, 0) \) post-shift.
- The vertical asymptote, previously at \( x = 0 \), is moved to \( x = 2 \).
Domain of Functions
The domain of a function is the set of all possible input values (or \( x \)-values) that the function can accept. Understanding the domain is crucial for effectively working with functions, particularly involving logarithmic operations. For the function \( y = \ln(x - 2) \), determining the domain involves:
- Identifying constraints within the function that restrict the possible values of \( x \).
- Since logarithmic functions like \( y = \ln(x - 2) \) require their argument \((x - 2)\) to be positive, solve the inequality \( x - 2 > 0 \).
- This inequality simplifies to \( x > 2 \), meaning the function is only defined for \( x \)-values greater than 2.
- The result is a vertical asymptote at \( x = 2 \), where the function approaches infinity as \( x \) approaches this asymptote from the right.